An empty chessboard may inspire some players with visions of stunning checkmates, intricately choreographed ambushes, strategic feints and traps, elegantly winning responses to a competitor's subterfuge. But one chess player saw a different kind of challenge in the board: each square prescribed a murder he had to carry out, and the rival he sought to beat was none other than the most prolific serial killer in modern history.

Alexander Pichuzkin, 33, is set to go on trial in Moscow for the murder of 51 people. He will almost certainly insist that he killed more. He may even point to the chess diagram he drew in a notebook, each square marked with a date: 61 were filled in, three short of the entire chessboard. The police say they cannot find evidence for that number of bodies dead at Pichuzkin's hands. Many of the grocery-shelf stocker's presumed victims were among Moscow's homeless, lured into a game of chess in a suburban park with glasses of vodka and mournful tales of Pichuzkin's beloved but deceased dog; then they were clubbed on the head with a hammer and tossed into a sewage pit to drown, if they were not dead already.

The victims, mostly older men, were easy prey in a quest that began in 1992 when Pichuzkin, then 18, says he killed a romantic rival. It was the same year that Pichuzkin's true rival, Andrei Chikatilo, the so-called "Butcher of Rostov," was tried and convicted for the murder of 53 women and children. Chikatilo, a terrifying figure who found sexual gratification in the mutilation of innocents, was the grandmaster of murder Pichuzkin sought to defeat and replace.

He has not been shy about admitting to his crimes. Pichuzkin detailed his exploits in a televised confession that aired shortly after his arrest in June 2006, following a five-year stretch of killings that plagued the neighborhoods around Moscow's vast Bitzevsky Park. "For me, a life without murder is like a life without food for you," he declared. "I felt like the father of all these people, since it was I who opened the door for them to another world." At one point, furious that the police had cast their suspicion on another person, he promptly went out and killed two more derelicts. He could be especially cruel. The body of one woman was found with tiny stakes hammered into her skull and around her eyes.

Pichuzhkin said he made his first kill when he was 18. At the time, he said he was conducting an affair with a girl named Olga, who lived next door. When she dumped him up for a mutual friend named Sergei, Pichuzkin says he killed Sergei by throwing him out a window. Though he was originally under suspicion, Pichuzkin says police finally concluded that Sergei's death was suicide. He did not kill again until five years ago, when the Bitzevsky Park murders started. Pichuzkin now claims to have killed his former girlfriend Olga as well, apparently after luring her into Bitzevsky Park.

The police, who arranged for the airing of the confession, were at first skeptical of Pichuzkin's stories. But three of the homeless men he chucked into the sewer survived; and one was lucid enough to identify Pichuzkin and to corroborate his modus operandi. And Pichuzkin's final victim  a co-worker at his grocery store  was skeptical enough about his tale of wanting to show her his dog's grave in the park that she told her son where she was going and gave him Pichuzkin's cellphone number. Pichuzkin was also caught on a subway surveillance cameras with the victim, and when confronted with the taped evidence, he confessed to everything. Proudly, though he did admit to some hesitation about his final murder. "As were heading to the park and talking, I kept thinking whether to kill her or take caution. But finally I decided to take a risk. I was in that mood already."

Might Pichuzkin have been mentally ill and thus not fully responsible for his actions? His mother says that Pichuzhkin, whom she raised alone after her husband abandoned the family, might have been affected by a blow to the head at the age of four; and also by the sudden loss of his grandfather, the only paternal figure in his life. But Russia's preeminent psychiatric institution examined him and declared him sane and fit for trial. Now a jury must decide if his boasts are true and, if so, how to punish him. They cannot sentence him to death. Russia has suspended capital punishment since 1996. Unless the state reactivates the death penalty, Pichuzkin will not be able to match Chikatilo's finale. The Butcher of Rostov was executed in 1994.

"I'm a great fan of chess," Pichuzkin told the police as he handed over his diary to the police. Indeed, his neighbors and friends confirm he was good at resolving problems on a chessboard, a talent to boast about of in chess-mad Russia. But he turned into bloodsport what a Nabokov character saw as an existential revelation. In The Defense the novelist wrote of one chess-obsessed character's epiphany: "...he had seen something unbearably awesome, the full horror of the abysmal depths of chess. He glanced at the chessboard and his brain wilted from hitherto unprecedented weariness. But the chessmen were pitiless, they held and absorbed him. There was horror in this, but in this also was the sole harmony, for what else exists in the world besides chess?" With reporting by Yuri Zarakhovich/Moscow